libtablet: Simplify tablet_create_version_cache

* Sort output instead of input;
* Ignore missing page dirs, this may happen if installwatch fails to run
  for non-staged spells, but we can at least use the version.
* Remove awk code, just make a list of broken spells in a file.
* Update error message.

scribe: Fix colouring and excess white-space

libmedia: Reset color with PROBLEM_COLOR

sightsee: Add a special case for Gitlab

sightsee: Add matching for Debian-style tarball names

sightsee: Add special case for Github

sightsee: Add {spell}-{version}-sources[.]... to the regex

install: Fix arch-prefixed symlink installation

install: Add clang to compilers

libgpg: Fix LANGUAGE overriding LC_ALL

Fixes: da2b9f84a380 ("libmisc: introduce get_safe_locale and use it in cast, libgpg", 2020-03-18)
Fixes: 496fc22b0037 ("Fix build issues related to non-UTF-8 LC_ALL", 2018-03-10)
Fixes: 7aafabba713f ("libgpg: set LC_ALL=C for commands output of which we parse #14705", 2008-09-02)

Fix version bumping

- Revert back to parsing tags, but match version tags only
- Add timestamp (from commit date) to snapshots

Fixes: 468486f77bb3 ("Makefile: version bumping for devel")

Makefile: Make filename depend on branch

- Removes the $(shell ...) GNUism.
- Stable releases get called: sorcery-x.y.z.tar.bz2
  (x.y.z comes from etc/sorcery/version)
- Other branches get called: sorcery-${BRANCH}.tar.bz2

Makefile: version bumping for devel

Starting 1.17

libdepengine: ignore pre_remove and post_remove failures for failure detection

The loop prevention hack guessed wrongly that a pre_remove failure is
serious and hence caused lots of spells being dropped once e.g.
grep was cast, which has a PRE_REMOVE that returns non-zero (something we could
investigate). Sorcery ignores that return value also for post_remove, but
the runtime mechanism still stores the failure reason.

Maybe we should ignore that failure reason log altogether. But I think I
had a reason including it.

We need to rewrite this all ...

This commit also makes the two messages different, adding 'subtly' for the
cases where the spell didn't outright fail but still has a reason (conflicts
is one remaining case which we might want to settle) and listing the
found reasons. This mainly should aid debugging once we get rid of these
cases. Either there is a failure or not, please.

resurrect: fix for symlink on /var/cache/sorcery

Revert "Implement logging by reusing file descriptors"

This reverts commit e9a142540638bf09792acc31fd8d715e3b59d962.

sightsee: Use CODEX_ROOT

libgrimoire: Simplify setting size in mk_source_dir

Implement logging by reusing file descriptors

Avoid opening files, references to /proc/self/fd/ may cause permission
issues when dropping privileges.